Misc: These letters define what - MASH?

Questions

Cattle are the only mammals that are retro-mingent (they pee---------- ).?

Certain ---------- emit a light so penetrating that it can pass through flesh and wood.?

Certain fireflies emit a light so penetrating that it can pass through ---------- and wood.?

Certain fireflies emit a light so penetrating that it can pass through flesh and---------- .?

Certain ---------- can be frozen solid then thawed, and continue living.?